The striped anemone, Diadumene lineata, is a small, greenish anemone with
white or orange stripes and usually 50-60 (and as many as 100) fully retractile, transparent or
slightly colored tentacles. The body is smooth and cylindrical (Eldredge and Smith 2001).
A number of distinct morphs of this species, based on body color and stripe
pattern were identified several decades ago, although these may actually
represent points along a gradient in appearance (Uchida 1932, Shick and Lamb
Potentially Misidentified Species
Diadumene lineata may be potentially confused with other co-occurring
anemones in the IRL, such as the pale anamone (Aiptasia pallida) and the
warty anemone (Bunodosoma cavernata). The body of A. pallida is pale to brownish,
more slender than that of H. lineata and lacking vertical stripes, possesses about half as many
tentacles, and often irregular has pale rings around the tentacles. The
tissues of A. pallida also typically harbor sumbiotic photosunthetic
zooxanthellae, discernable vie microscopic examination. B. cavernata is
typically brownish green with pale bluish columnar dots (warts) on its body.
HABITAT AND DISTRIBUTION
Diadumene lineata occurs intertidally to subtidally on solid substrata in
This U.S. non-native, presumed to have come from a native range encompassing
the Pacific Coast of Asia, now occupies suitable marine habitats throughout the
northern hemisphere. Introduced populations are known to occur in the British
Isles and in Western Europe, in the Mediterranean Sea, and on both coasts of
North America (Barnes 1994, Cohen 2005). On the U.S. east coast, the species
can be found in Maine and from Massachusetts to Florida. (Shick and Lamb 1977).
H. lineata has also been previously collected in Texas and from the
Suez Canal but appears not to have become established in these locations (Cohen
Diadumene lineata is likely to occur throughout the IRL basins where hard
fouling surfaces such as rocks, pier pilings, boat hulls, mangrove roots, and
oyster shells are available.
LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan
Diadumene lineata is a small anemone, typically less than 4 cm in height and with
a tentacular crown of around the same size (Eldredge and Smith 2001).
Localized Diadumene lineata populations are often ephemeral as well as irruptive, suddenly
appearing in sizeable numbers and then after a time disappearing just as
abruptly (Shick and Lamb 1977).
Like other anemones, Diadumene lineata can reproduce asexually or sexually
(Slick 1991, Coheh 2005). Asexual propagation may be by means of longitudinal
fission (splitting in half along a vertical plane) or through pedal laceration
(pulling away from its point of attachment and leaving bits of tissue to be
regenerated). Sexual reproduction occurs through the release of gametes into
the water column and subsequent external fertiliztion (Shick and Lamb 1977).
Carlton (1979) indicates that sexual reproduction occurs only infrequently outside of this species' native
Embryonic development in Diadumene lineata occurs via a free-living planktonic
stage persisting in the water column for an unknown duration.
Diadumene lineata is broadly eurythermal, as evidenced both by its latitudinal
range and by its ability to survive intertidal exposure to extreme summer and
winter temperatures in parts of its range (Shick and Lamb 1977).
Different localized populations within the broader regional landscape exhibit
very different and locally adaptive responses to extreme temperatures. For
example, at 10°C H. lineata populations in Virginia exhibit reduced metabolic
activity and protect themselves through encystment in mucus whereas
cold-adapted Maine populations remain metabolically active at 0°C and below
(Sassaman and Magnum 1970, Shick 1976).
H. lineata in San Francisco Bay experience annual temperatures between
14-24°C (Cohen 2005).
The intertidal Diadumene lineata is euryhaline, able to cope with large salinity
reductions when they occur [see references in (Shick and Lamb 1977). San
Francisco Bay populations typically experience salinities ranging from 18-34
ppt. Individuals from these populations may succumb to prolonged exposure to
lethal salinities below 12 ppt.
Intertidally located Diadumene lineata can retract their tentacles and contract
into globular hemispheres to minimize exposure and possible desiccation.
Encystment in mucus may also be employed during periods of prolonged exposure,
and this trait may enhance the ability of the species to survive long-distance
accidental transport (Cohen 2005).
Diadumene lineata is a carnivore that preys largely on water column protists
and small crustaceans and other invertebrates (Bumann 1995).
Unlike many past marine introductions, the historic spread of H. lineata
to U.S. waters is well chronicled with the earliest biogeographic records
dating to New Haven, Connecticut in 1892. Carlton (1979) indicates that this
western Pacific (Japan, China, and Hong Kong) native was also present on the
Pacific coast of North America within a decade of its arrival on the east
Human-mediated dispersal modes historically contributing to the spread of the
species include attachment to ship hulls and accidental inclusion in commercial
shipments of oysters and seaweed (Shick and Lamb 1977, Gollasch and
Riemann-Zurneck 1996, Cohen 2005). Hull fouling from Japan is the likely source
of the initial east coast introduction while oyster shipments (Crassostrea
virginica) from the Atlantic states to California likely led to
introduction within san Francisco Bay. Hull fouling from New England probably
led to introduction of H. lineata in Great Britain which had been
confirmed by 1896.
Physiological tolerance with regard to several abiotic factors (see above),
combined with the ability to propagate asexually are likely key reasons for the
success of H. lineata as an invasive species (Gollasch and
Potential to Compete With Natives
Competitive interactions between introduced Diadumene lineata and native
species have not been studied, but are presumed to be minimal.
Possible Economic Consequences of Invasion
The economic impacts of H. lineata introduction have not been studied, but are presumed to be minimal.
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